After you are revered, Wrathion will call you back to tell you what he has learned about Varian. This is seemingly where the quest line stops for now. It may be incomplete, as the Horde side of the quest line is not even added yet.

Alliance Questing: Operation: Shieldwall
This is the start of the Alliance quest line in Patch 5.1. This line involves the new Operation: Shieldwall faction.

Horde Questing: Operation: Shieldwall
This is the start of the Horde quest line in Patch 5.1. This line involves the new Dominance Offensive faction.

World PvP Objectives
While you are doing those daily quests, it will be helpful to capture some of the world PvP objectives. Holding the objectives provides some helpful buffs that make questing faster:

Oil Baron - Grants 10% increased run speed, and reduces cast time of all mount spells by 75%.

Brawler's Guild Preview
Patch 5.1 adds a new activity, the Brawler's Guild. It is located in an instanced area in Stormwind or Orgrimmar. Upon entering the area you can see the arena where the current fight is taking place if there is one, along with any other spectators, the Brawler's Guild NPCs to queue from, and the Quartermaster.

Only one player can fight at a time, so you must queue for battle with one of the NPCs. When it is your turn, you enter the ring and fight a somewhat difficult mob. Each win gives you reputation to raise your ranking. There are a total of eight ranks to progress through, with many wins needed to go up through each rank.

Brawler's Guild Invites
The new Brawler's Guild being added Patch 5.1 will require you to purchase an invite from the Black Market Auction House or get one as a drop. If you aren't able to purchase an invite, someone else who is already in the Brawler's Guild can invite you. On the PTR there are currently 10 invites with a starting bid of a 1,000 gold.

New battle stones have been added to allow you to upgrade pets. It will cost you 1000 Justice points or a rare drop after a battle with a wild pet to upgrade to uncommon. Rare stones can also be obtained as a rare drop after defeating a wild pet, or from the Sack of Pet Supplies that are rewarded by Pet Battle quests.

The Pet Journal also has several updates, with better filtering, searching, and the rarity of each pet being shown without any addons. There are several other smaller changes being made, such as an increase to a cap of 650 pets or pet quality being displayed in battles. Read the full notes to see the full list of changes and check out the screenshots below for the UI improvements!

Loss of Control Alerts
Patch 5.1 adds alerts when you lose control of your character to the default UI. They tell you what is affecting your character and the remaining duration.

New Scenarios
Patch 5.1 adds several new scenarios, all of which have a faction specific version.

New Darkmoon Faire Music
New music for the Darkmoon Faire was added in Patch 5.1!

The conflict between the Horde and the Alliance has ignited a new series of daily quests along the shore of the Krasarang Wilds.

Players can visit their faction strongholds in the Vale of Eternal Blossoms to begin the quest to summon their war fleets to the continent of Pandaria.

Players will both valiantly defend their faction’s outpost and assault the opposing faction's headquarters.

Two new Reputations have been added: Alliance players can earn reputation with Operation: Shieldwall, while Horde players will curry favor with the Dominance Offensive.

Players can follow the story of the Pandaren Campaign through a series of special quests tied to their reputation with the landing forces. Heroes assisting with the war effort will join key characters and faction leaders as the growing conflagration spreads across Pandaria... as well as other locations around Azeroth.

Players can slay rival NPCs and opposing faction players along the shore to earn commissions that can be spent to upgrade their faction's base.

Look for strategic objectives to capture, including graveyards and towers. Commissions can be spent to recruit guards that will help protect this captured territory!

Players who are truly dedicated to their faction can spend their commissions on an item that will give their fellows an extra reputation group quest for the day. Horde players can speak with Ongrom Black Tooth, while Alliance players can contact Proveditor Grantley for details.

Item Level Upgrades

Players can now use PvE and PvP currencies to directly upgrade equipment by visiting Ethereal merchants in their respective Pandaria faction capitals.

Weapons and armor of item level 458 or higher can be improved by up to 8 item levels each.

Be aware that items that have received item level enhancements cannot be placed into Void Storage.

Legendary Quest

Wrathion has taken a keen interest in the events along the coast of the Krasarang Wilds. Those that have aided the Black Prince in the past will now have new quests to complete as they advance Wrathion’s agenda for Pandaria and their own progress toward Legendary power.

Brawler's Guild

Underground fighting rings have sprung up in Stormwind and Orgrimmar that will give brawlers who have their mitts on an invitation a chance to earn bragging rights by testing their solo PvE mettle against some of the toughest creatures found in World of Warcraft.

Players will prove their skill, and increase their rank with the Brawler's Guild, as they win matches against some of the most difficult solo encounters in World of Warcraft.

Entry into the brawler’s guild is by invitation only. Invitations can be found on the black market auction house, by invitation from somebody within the guild, and occasionally as drops from certain Horde and Alliance NPCs.

As their Brawler's Guild rank increases, players will unlock additional rewards and activities within the Brawler’s Guild.

Brawlers on a realm will gather together into the blood spattered ring to watch as their peers face down their own opponents. They can watch the battles in progress to learn from hardened Brawler's Guild veterans as they wait for their own turn to fight.

If this is your first night at Brawler's Guild, you have to fight.

Lesser Charms of Good Fortune no longer take up bag space, and are now recorded in the currency tab of the Character Sheet.

Grand Commendations are now available for purchase from all Mists of Pandaria faction vendors at Revered reputation. Using a Grand Commendation will permanently increase the amount of reputation gained with that faction across all characters on a Battle.net account.

A new passive ability has been added: Tooth and Claw. This ability causes autoattacks to have a chance to empower the Druid's next Maul. Empowered Maul reduce the damage dealt by the target's next autoattack. Guardian Druids obtain this ability at level 32.

All totems are now considered spells, and summoning totems can be prevented by silencing effects. Searing Totem, Magma Totem, and Fire Elemental Totem fall into the Fire school, while all other totems fall under the Nature school.

Items

Spirit of Harmony can now be purchased for 600 Conquest Points at the Conquest Quartermaster.

Item Enhancements

The Dancing Steel, Jade Spirit, Colossus, and River’s Song enchantments now use the Real PPM system utilized by Windsong and Elemental Force.

Pet Battles

A new item has been introduced that can be used to upgrade the quality of Battle Pets: Battle-stones.

Battle-stones are available in two basic types, general purpose Battle-stones that can be used to upgrade the quality of any pet, and family specific Battle-stones, which can only be used to upgrade pets of a specific pet family.

Battle-stones are available in two qualities: Flawless Battle-stones can upgrade pets directly to Rare quality, while Polished Battle-stones will upgrade a pet to Uncommon quality.

Players will have a very small chance to obtain a general purpose and family specific Flawless Battle-stone after winning a match against wild pets; defeating higher level opponents increases the chances of obtaining a stone. Family specific Flawless-Battlestones will be of the same family as the pets that were defeated. These valuable items are not soulbound, and can be sold on the Auction House.

Family specific Flawless Battle-stones can be found in the Sack of Pet Supplies obtained from performing Pet Trainer quests, and are Bind on Pickup.

General purpose Polished Battle-stones can be purchased for 1000 Justice Points.

Pet Journal

The quality of each pet is now visible in its slot in the Pet Journal.

Pets can now be filtered by name, type, rarity and level, and filters will remain in place each time the Pet Journal is viewed.

It is now possible to search locations in the Pet Journal. For example, searching “Westfall” will display all the Battle Pets that can be found in Westfall.

Pet Battle music is now more appropriate for the type of match being fought.

Several new Pet Battle PvP areas have been added to the world.

Several classic Raid bosses now have a chance to drop new Battle Pets. The new pets can be obtained from bosses in Molten Core, Blackwing Lair, Ahn'Qiraj, and Naxxramas.

Abilities that have been used will now continue to cool down for pets when they are not the active pet in a battle.

Right clicking a pet's portrait will now offer the option to look it up in the Pet Journal.

Players can now keep up to 650 pets.

Battle Pet tooltips will now display whether a pet is owned, and how many pets of that type are owned.

Pet Quality is now displayed in battles, and will be visible on portraits, names and tooltips.

The level of battle pets in a zone can now be seen on the map, and it’s now possible to see the strength of wild pets relative to your team at a glance.

Backline pets now display debuffs affecting them as well as the remaining duration of these effects.

The experience multiplier obtained by all seven Grand Master pet trainers in Pandaria has been increased to x5 from x3.5.

The experience multiplier obtained by defeating Pet Trainers Julia Stevens, Old Macdonald, Zunta, and Dagra the Fierce has been reduced to x2.5 from x3.5.

Macros have been added that allow for summoning random pets and random favorite pets.

The achievement Taming the World now awards the Safari Hat, which increases pet experience gained from Pet Battles by 10%.

Pets previously removed from the Safari achievements have been added back to the criteria of those achievements now that they're back in the wild.

The I Choose You achievement has been added for defeating Zen Master Aki. The reward for this achievement is 3000 gold.

Players that defeat Aki the Chosen at the culmination of the Battle Pet quest lines can now follow a new line of Battle Pet quests and associated daily quests that allows players to battle against Pandaren spirits.

A new Master Pet Tamer offering daily quests has been added to the Darkmoon Faire. Completing quests for the new trainer will offer the chance to acquire a new pet: the Darkmoon Eye.

The Dragon Kite can now be used in Pet Battles.

The Imperial Silkworm and Imperial Moth pets can now be created by Tailors.

A number of pets that could previously only be found accompanying other pets into battle can now be found roaming the world.

A number of new capturable pets can be found in the world from pet families that were once more sparsely populated.

Two new Battle Pets now roam Darkmoon Island waiting to be caught.

Fixed an issue that would prevent some pets captured in Pet Battles from correctly saving their skin color once added to the Pet Journal.

Player versus Player Pet Battles now award more experience.

Large plants and bushes in the environment that interfered with visibility during Pet Battles while now fade out of view during the match.

Fixed an issue where the Gazelle would join pet battles.

Sunsong Ranch

A new Seed has been added: Portal Shards

A mage who fell on hard times back in Dalaran has found a new home on Pandaria. Barnaby Fletcher will occasionally visit Halfhill Market to peddle a new type of seed – and take advantage of the Tillers’ hospitality.

Portal Shards grow into consumable items which can be used to open a portal from Sunsong Ranch to a major faction city.

Seeds now stack to 50.

Runty crops now have a spell visual to help call attention to themselves.

Growing crops now display the duration until the crop is ready to harvest.

Characters who have earned the “Friends on the Farm” achievement will no longer find gifts while harvesting Cooking Ingredient crops – instead, they have a chance to find special seeds such as Magebulb, Enigma Seed, Songbell, and more.

Raids, Dungeons and Scenarios

Non-boss enemies in Mogu'shan Vaults, Heart of Fear, and Terrace of Endless Spring now respawn much more slowly.

Raid groups are no longer necessary to enter pre-Mists of Pandara raid dungeons. Enemies in these raids that previously required more than one player to defeat are now more easily dealt with by players battling alone.

Cooldown timers greater than 5 minutes will now reset between attempts on Challenge Mode dungeons.

Scenarios

New level 90 Scenarios have been added, including additional faction specific Scenarios:

Assault on Zan'Vess

Alliance

Lion's Landing

A Little Patience

Horde

Domination Point

Dagger in the Dark

Scenarios now include Dungeon Finder queue features, including leaders, backfill, vote to kick, and deserter debuffs. Roles are still not required.

PvP

The growing conflict between the Horde and the Alliance has spilled across the face of Azeroth: level 90 players can now queue for Wintergrasp and Tol Barad via the PvP tab to battle one another in these epic conflicts.

Arena matches now have a 25 minute time limit (was 45 minutes).

Rated Battlegrounds now share the same spell restrictions as Arenas.

Professions

Cooking

A cooking profession bag has been added, and can be purchased with Ironpaw Tokens from Nam Ironpaw.

Mining

All mineral nodes will now despawn one minute after they are mined, even if items remain in them.

UI

Justice, Valor, Honor and Conquest Point quartermasters are now signified by new minimap icons.

A new banner will appear when a player is subjected to an effect that causes them to lose control of their character. The effect that caused the loss of control and remaining duration will be displayed. Configuration options are available in the “Combat” section of the “Interface Options" menu.

A search bar has been added to the mount section of the Mount and Pet Journal.

The Mount and Pet Journal remembers which tab you were last using.

Bug Fixes

Swooping Plainshawks no longer use abilities from the Bird of Prey Hunter pet family.

Fixed an issue that could cause crops to fail to appear when players entered Sunsong Ranch while several hundred yards up in the air.

Players who have learned the Terrible Turnip pet can now continue to find Ominous Seeds when harvesting Cooking Ingredient crops.

Dominance Offensive (New) Complete the Dominance Offensive storylines listed below. 10 points. Criteria: Blood For Blood, Domination Point, The Voice of the Gods, The Horde Is Family, The Korune, Pride, Rise of the Blood Elves, Secrets of the Past, The Divine Bell, The Darnassus Operation, Breath of Darkest Shadow, The Purge of Dalaran.

Operation: Shieldwall (New) Complete the Operation: Shieldwall storylines listed below. 10 points. Criteria: The Korune, Lion's Landing, The Man With a Thousand Faces, The Voice of the Gods, Jaina's Hope, Heart of the Alliance, Secrets of the Past, An Ancient Ally, The Purge of Dalaran, The Divine Bell, In Search of Harmony, Breath of Darkest Shadow.

Reputation

Wakener (New) Become an honorary Klaxxi Paragon by completing the achievements listed below. Title Reward: the Wakener. 10 points. Criteria: Amber is the Color of My Energy, Klaxxi.

Help out by checking the box in the Curse Client options as seen below. When you are playing the addon will gather data and save it. When you are done playing, Curse Client will see the game close and upload the collected data from the addon.

I think it's pretty cool that the skyfire quest in Jade Forest hinted that the patch would be released in two months. I think blizzard should do more things like this.

Also, I think gating the raid content was a great idea. It makes me feel like I'm getting "new" content almost every week. Especially since 5.1 is coming out 1 week after the last set of heroic bosses were released. I hope that blizzard will be able to continue pushing out content at such a fast pace.